Quasielastic Scattering of the Halo Nucleus ^6He at 25 MeV／u from a ^9Be Target

The differential cross sections of quasielastic scattering of a 25 MeV/u ^6He from ^9Be target have been measured.The double-folding model approach is applied to generate the real part of the optical potential. The imaginary potential parameters as well as some of the real potential parameters are studied in comparison with the experimental data. The effect of the unstable nucleus is discussed.     

25MeV/u6He+9Be反应的轻粒子发射

在25MeV/u ⁶He与⁹Be靶的反应中,107°和128°处明显地观察到了轻粒子发射.粒子能谱形状与平衡热源蒸发相一致,分析得到热源的核温度为完全熔合条件下的5.6MeV或非完全熔合条件下的5.2MeV .实验发现发射氚的数量特别大,这可能与目前广泛研究的⁶He的集团结构和同位旋效应有关.     

Raman spectroscopic study of ceramic Sr2Bi4Ti5O18

Raman spectra of ceramic Sr2Bi4Ti5O18 （SBTi5） are reported to consist of four different Raman bands. Temperature-dependent spectra reveal the relationship between the lattice vibration and the material＇s structure. There appears a relatively large change in structure of the material at about 273K, The anharmonic potential of the material has a great influence on its phonon mode full width at half maximum （FWHM）, which can be expressed by a function of temperature. Theoretical fittings of the FWHMs for the two modes at around 312 cm^-1 and 464cm^-1 indicate that the latter phonon mode is more anharmonic than the former one.     

ZnO微晶的水热合成及形貌控制研究

以Zn(NH3)4(Ac)2为前驱体,不加任何模板剂和表面活性剂,低温下通过改变反应条件(如前驱体浓度、反应时间及反应温度),实现了对ZnO微晶形貌和尺度的有效控制.所得花状、蜂窝状、柱状ZnO用X射线衍射仪和扫描电镜进行了鉴定和表征,并初步探讨了不同形貌ZnO微晶的生长机理.     

含吗啉基片段的水杨醛席夫碱类化合物的合成及其淬灭1,1-二苯基-2-三硝基苯肼自由基性能

通过3-氟-4-吗啉基苯胺和取代水杨醛缩合反应,合成了14个含吗啉基片段水杨醛席夫碱类化合物(Ⅰa-Ⅰn)。通过核磁共振波谱仪(NMR)、傅里叶变换红外光谱仪(FTIR)、液相色谱-质谱联用仪(LC-MS)和元素分析等技术手段研究了产物的结构和淬灭1,1-二苯基-2-三硝基苯肼(DPPH)自由基的活性。 结果表明,在0.02~0.10 g/L,所有化合物均表现出一定的淬灭DPPH自由基活性。 其中,化合物Ⅰd和Ⅰf表现出较为优异的性能,化合物Ⅰd的活性在30%~55%,化合物Ⅰf的活性则大于50%。 随着化合物Ⅰd、Ⅰh、Ⅰj和Ⅰn质量浓度的增大,其淬灭DPPH自由基的活性均呈现增强趋势。     

脉冲电场测试中的激光供电技术

为解决脉冲电场测试系统中的供电问题，设计了一套激光光纤供电系统，该系统由激光器、多模光纤及光电池构成。重点研究了激光器与光纤的耦合问题，设计了透镜系统对激光器输出光束进行准直和压缩。通过MOCVD法研制了GaAs光电池，并制作了椭球形"光伏眼"来提高光电转换效率。仿真和实验表明:采用透镜耦合时，激光器与光纤的耦合效率可达80%以上，远远高于直接耦合时的16%，改进后的"光伏眼"耦合效率相比直接耦合时提高了54.5%，激光供电系统的转化效率在40%以上。该系统的研制为解决脉冲电场的供电问题提供了一种方案。     

N'-(2-羟基-5-甲氧基苯甲基)-4-二甲氨基苯甲酰肼及其氧钒(V)配合物:合成、晶体结构和脲酶抑制活性

制备了一个苯甲酰腙化合物N'-(2-羟基-5-甲氧基苯甲基)-4-二甲氨基苯甲酰肼(H₂L).利用H₂L、乙酰氧肟酸(HAHA)和VO(acac)₂在甲醇中反应得到了配合物[VOL(AHA)].通过元素分析、红外和紫外光谱,以及单晶X-射线衍射对H₂L和其配合物进行了表征。苯甲酰腙配体作为二价阴离子,利用其酚羟基氧原子、亚胺基氮原子、以及烯醇氧原子与V原子进行配位.乙酰氧肟酸配体利用其羰基氧原子和去质子化的羟基氧原子进行配位.配合物中的V原子为八面体配位构型。测试了H₂L、HAHA和钒配合物的脲酶抑制活性.在浓度为100 μmol·L^-1时,钒配合物对幽门螺旋杆菌脲酶的抑制率为63%,其IC₅₀值为45μmol·L^-1.还利用分子对接技术研究了配合物分子与脲酶的作用方式.     

几种声学参数在艺术嗓音客观评价中的应用

在艺术嗓音客观评价中,评价声学参数的选取至关重要。尝试利用语音分析技术提取歌声平均能量、平均频率误差、平均音域误差作为客观评价声学参数,使用神经网络方法客观评价艺术嗓音歌声质量,并与资深专业教师的主观评价进行比较。结果表明,综合使用三个声学参数能正确客观评价歌声质量,评价误差在4%之内,有助于科学地指导选拔、培养和训练艺术嗓音人才。     

Near-Field Fluorescence and Topography Characterization of a Single Nanometre Fluorophore by Apertureless Tip-Enhanced Scanning Near-Field Microscopy

Tip-enhanced near-field fluorescence and topography characterization of a single nanometre fluorophore is conducted by using an apertureless scanning near-field microscopy system. A fluorophore with size 80hm is mapped with a spatial resolution of 10hm. The corresponding near-field fluorescence data shows significant signal enhancement due to the apertureless tip-enhanced effect. With the nanometre spatial resolution capability and nanometre local tip-enhanced effect, the apertureless tip-enhanced scanning near-field microscopy may be further used to characterize a single molecule by realizing the local near-field spectrum assignment corresponding to topography at nanometre scale.     

Ultradilute self-bound quantum droplets in Bose–Bose mixtures at finite temperature

We theoretically investigate the finite-temperature structure and collective excitations of a self-bound ultradilute Bose droplet in a flat space realized in a binary Bose mixture with attractive inter-species interactions on the verge of meanfield collapse. As the droplet formation relies critically on the repulsive force provided by Lee–Huang–Yang quantum fluctuations, which can be easily compensated by thermal fluctuations, we find a significant temperature effect in the density distribution and collective excitation spectrum of the Bose droplet. A finite-temperature phase diagram as a function of the number of particles is determined. We show that the critical number of particles at the droplet-to-gas transition increases dramatically with increasing temperature. Towards the bulk threshold temperature for thermally destabilizing an infinitely large droplet, we find that the excitation-forbidden, self-evaporation region in the excitation spectrum, predicted earlier by Petrov using a zero-temperature theory, shrinks and eventually disappears. All the collective excitations, including both surface modes and compressional bulk modes, become softened at the droplet-to-gas transition. The predicted temperature effects of a self-bound Bose droplet in this work could be difficult to measure experimentally due to the lack of efficient thermometry at low temperatures. However, these effects may already present in the current cold-atom experiments.